Induction motor



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.1. B. GURY, JR., `ET AL O INDUCTION MOTOR Filed FOB. 4,

i9?) 2 Sheets-Sheet 2 Patented Nov. ll, 1924.l

UNIHTED STATES l "1,515,478 PATENT OFFICE.

JOHN B. GURY, JB., A NID ROBERT H E. SCHLECHT, 0F ST. LOUIS, MISSOURI.

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Application lcd February a, 1921. Serial No. 442,377.

To all whom it may concern:

Beit known that we, JOHN'B. GURY, Jr., and ROBERT H. E. SCHLECHT, citizens of the United States, and residents of the city of 5 St. Louis and State of Missouri, have invented a certain new and useful Improvement 'in Induction Motors, of which the following is a specification. i

This invention relates to induction motors, and it has more particularly to do with the control of the starting coils of singlephase motors of this type.

It is Well known that a single-phase induction motor or one provided withonly a single winding on the field, instead of two or more sets of windings diiering in phase, will not start up of its own accord when connected to single-phase mains, but if the armature or rotor is given a start by hand or otherwise, it will continue to rotate an gradually come up to speed in whatever direction it is thus started.

stator or ield--andfis-commonl In some motors of this type, an auxiliary or supplemental winding is provided in the known as coil. his windin the teaser or starting e mam winding an is of ner wire' than t of very high resistance. Consequently, it is liable to burn outl if maintained in action indefinitely or. even for a reasonably short time after the motor is up to speed or in full step. Furthermore, it is not needed in the operation of the motor after the rotor is Yonce started.

Mechanical devices have been rovided to open the usual normally close the device acts, and, in any case, the struc-v ture is more or less complicated and embodies several diierent working parts.

The present invention has for its objects to minimize'the number of mechanical working parts and to produce a simple contrivance which is ma netically controlled and actuated rather gian mechanically; and, further, to secure a quick release of the starting coil after the rotoi is started as 'well as attain certain advantages as will hereinafter more fully appear.

The present invention comprehends broad- 1y the utilization of a magnetically concircuit 'of the startin coil after the motor has gotten trolled circuit closer in a normali open circuit for the starting coil, where y the cir-v l said circuit c oser including an actuator element or contrivance which is located on the motor in proximity to a pole-piece but is attracted only by an excess of magnetism aboveA a certain minimum and is self-restored to normal position as soon as the said minimum is reached, or in other words, when the motor has gotten into'step or up to speed.

In the accompanying drawing,- Figure 1 is a diagram of the main field and starting coil windings of an ordinary two-pole, single-phase, induction motor having a circuit control for the starting coil according to the present invention;

Figure 2 is a detail view of a modification ofthe circuit closer;

Figure 3V is a'fragmentary view of a polepiece, showin how the 'modified circuit closer is place in the motor;

Figure 4 is a diagram of an arrangement of the circuit closer for reversing the direction of rotation of the motor;

Figires 5 and 6 are detail diagrams showing t e wire connections which may be effected to start the motor in different directions;

Figure 7 is a view partly in side elevation and partly. in lon itudinal section of the reversible circuit c oser; and

Fi e 8 is a view of the same partly in end e evation and partl in cross section.

Referring now to the rawing, the numeral 1 designates the main field winding and the numeral 2 the starting coil winding. The armaturev 3 is of the usual squirrel-'cage t e. s f

yn the circuit for the starting coil winding (see F' ure l) is a circuit closer including a meta ic reciprocatory member 4 which is located in proximit to the center of the gole-piece of the fie d so as .to be attracted y the latter when suliiciently ma etized. This member 4 is mounted to sllde in a guide-block or bushing of non-conducting material 5 on the frame or casing of the motor 6 and it is yieldably held in normal f position by a spring 7 which is attached at'y one end to a blocker bushing of insulationff material 8 on the casing 6, while its oppo-I site `end portion extends through a transverse aperture in the member 4.

On the insulation block 5 are two terminal contact members 9, 10, respectively for the starting coil lead wires 2 and 2".

The spring 7 is of just sufiicient strength to resist the minimum attractive force of the magnetized field attained when the motor is in full step or up to speed.

When the current is first thrown into the main field coils the excess load magnetizes the field to a high degree, whereupon the member 4 is attracted and a metallic collar 11 thereon is drawn into contact with the terminal contact members 9, 10, thereby closing the starting coil circuit. The starb ing coil is thus energized and the rotor or armature is started, and, as soon as the rotor gets into step and the magnetism in the field thereby decreases, the member 4 is restored to normal position by the spring 7.

To secure a good electrical contact of the collar 11 with the terminal contact members 9, 10, it is slidably mounted on the member 4 and held normally in contact with a shoulder thereonV by a coiled spring 12. By this arrangement the collar is brought into engagement with the terminal contact members before the member 4 reaches the limit of its travel towards the field.

The controlling device may be placed conveniently on the motor frame or casing, but in some cases the modified structure shown in Figure 2 may be inserted in one of the channels of the pole-piece or field. In this modification the two terminal members 9* and 1()al are located in the opposite ends of a tube 13 of insulation material, and each terminal has a yieldable, spring-pressed contact 13HL opposed to which are a pair of slidable blocks 14 which are connected at their meeting ends by a spring 15 of conductinv wire. Loosely within the spring 15 is a rod 16 which is disconnected from said blocks 14 but serves as a spacer to prevent them coming closer together than a given distance.

In utilizing this modification the tube is inserted in the channel of the polepiece or field so that it extends across the same. The

spacing rod 16 keeps the blocks normally in proper range to be attracted in opposite directions and towards the outer ends of the tube when the excess load is on the field at the start.

'In both of the foregoing modifications the -yieldable contact members overcome vibrathe first form the motor is started in only one direction, while in the latter form provi` sion is made for startino` the motor in either direction. This reverssil of direction is accomplished by changing the ieads into the starting coil. On the insulation block 5 are four terminal contact members 17, 18, 19 and 20, the first two of which are diametrically opposed and are respectively connected by the wires 17* and 18l with the leads of the main field winding. The two other terminals 19, 20, are diametrically opposed and connected respectively to the terminal leads of the starting coil.

In this last modification provision is made on the yieldable collar 11l of the member 4* for connecting the terminal members in respective pairs 18, 19, andl, 20, at one and the same time, which will start the motor in one direction, and in pairs 17, 19, and 18, 20, respectively, which will start the motor in the opposite direction (see Figures 5 and 6).

To effect the adjustment for the change in direction, the member 4 is provided with a reduced portion or neck 21 which is square in cross section, which reduced portion is straddled by a bifurcated spring member 7'L serving not only to yieldably hold the mem ber in normal endwise position but also yieldably holds it from rotation. In this modification also the collar 11a is slidable on a square shank or neck portion of the member 4n to prevent it turning inde endent thereof but permitting it to be su ciently yieldable to secure a good `electrical contact with the terminal members on the block 5.

As hereinbefore stated, the invention comprehends broadly the idea of a magnetically controlled and operated circuit closer for the starting coil, and it therefore admits of considerable modification within its spirit as defined by the. appended claims, and is not to be limited to the specific constructions and arrangements shown in the drawing.

What is claimed is:

1. In an induction motor of the sin lephase type, having a main winding an a starting coil, the circuit of the starting coil being normally open, a magnetic clrcuit closer for said circuit, the same including an actuator element located in proximit to the center of a pole-piece of the mam field whereby to be attracted by the magnetized pole-piece but only while attractive force is in excess of a certain minimum, said actuator being self-restored to normal position when the said minimum of attractive fo is reached.

2. In a motor of the character described, in combination with the main field and the starting coil, a non-conducting support on the motor frame, said support having terminal contacts thereon for the starting coil leads, a self-retracting element mounted on said non-conducting support and being capable of electrically connectin lsaid terminal contacts, but being norma ly out of ment mounted on said'su'pport and having yieldable contact portions to electrically connectsaid terminalcontacts of the starting coil circuit, but being normally out of engagement x therewith, said self-retracting element bein "1in attractive range of .the main field w ereby to be attracted only during the existence *of excess magnetism in the main eld at the starting of the armature.-

Signed at St. Louis, Missouri, this'25th 25 day of Januar 1921.

,- JHN B. GURY, JR.I A

ROBT. H. E. SCHLECHT. u 

